rand: add 64-bit tausworthe variant with a 2^258 cycle

[fio.git] / lib / gauss.c

diff --git a/lib/gauss.c b/lib/gauss.c
index 5c3203c05754b8ae52b57aee6393b441a16050bc..afd0490d54786130acf04e0bb3c64bd8a4473bbd 100644 (file)
--- a/lib/gauss.c
+++ b/lib/gauss.c
@@ -15,7 +15,7 @@ static int gauss_dev(struct gauss_state *gs)
                return 0;
 
        r = __rand(&gs->r);
-       vr = gs->stddev * (r / (FRAND_MAX + 1.0));
+       vr = gs->stddev * (r / (FRAND32_MAX + 1.0));
 
        return vr - gs->stddev / 2;
 }
@@ -41,14 +41,15 @@ unsigned long long gauss_next(struct gauss_state *gs)
        return __hash_u64(sum) % gs->nranges;
 }
 
-void gauss_init(struct gauss_state *gs, unsigned long nranges, unsigned int d,
+void gauss_init(struct gauss_state *gs, unsigned long nranges, double dev,
                unsigned int seed)
 {
        memset(gs, 0, sizeof(*gs));
-       init_rand_seed(&gs->r, seed);
+       init_rand_seed(&gs->r, seed, 0);
        gs->nranges = nranges;
-       if (d) {
-               gs->stddev = (nranges * 100) / d;
+
+       if (dev != 0.0) {
+               gs->stddev = ceil((double) (nranges * 100.0) / dev);
                if (gs->stddev > nranges / 2)
                        gs->stddev = nranges / 2;
        }